Confused!

[GARVIT DANG]

I was making an excel file. In a cell I typed 5181011682693907(no spaces) which was then converted into 5.18101E+15 but when I typed the above no. as 51810116826 93907(space b/w 6 and 9) there was no issue. Please solve it for me.

[#2]

in excel there is a limit to numbers displayed in a cell - something about 15 digits only - longer than that it will be presented in a scientific notation like with the letter E.
if you want a full numbers then format it as TEXT ..
also you may want to visit this site:
https://support.office.com/en-us/article/excel-specifications-and-limits-1672b34d-7043-467e-8e27-269...
HTH